JLG 680S, Service And Maintenance Manual

Page: 389 / 530

SECTION 5 - BASIC HYDRAULICS INFORMATION & SCHEMATICS
3121234 5-53
Set Up the Function Pump
(The pump that is mounted on the back of the drive pump).
1. Set Stand by pressure or load sense pressure
a. Install a low pressure gauge at port “MP” of the
main valve block. A gauge capable of reading
400 psi (27.58 bar) .
b. Remove the wires from the main boom lift, valve
coils on the main boom main valve block. Start the
engine and activate main lift up or down. Hold the
function for 10-15 seconds. This bleeds the air out of
the sense line. The gauge should be reading
between
400-440 psi (28-30 bar) .
c. To make an adjustment to this pressure, go to the
engine compartment, locate the function pump.
There are (2) adjustments at the top of the pump.
They are located on the pump compensator which
has (4) bolts mounting it to the pump. The stand by
adjustment is at the top.
d. To adjust this, a 4 mm and 6 mm allen wrench will
be needed. The adjustment screw is facing the front
of the pump, or toward the engine. First, using the 4
mm wrench, loosen the setscrew on the side of the
compensator (facing you) which is in line with the
adjustment screw. This is a jam nut screw which
holds the main adjustment from turning. Loosen it 1
turn.
e. Then using the 6 mm wrench adjust the main
adjustment clockwise to increase or counterclock-
wise to decrease. The pressure should read between
400-440 psi (27.58-30.34 bar) .
2. Set High pressure relief
a. Install a high pressure gauge at the “MP” port of the
main valve block.
b. Activate main boom telescope in. The gauge should
read
2600 psi (179 bar) .
c. To make an adjustment to this pressure, go back to
the engine compartment to the function pump. The
high pressure relief adjustment is the lower one of
the (2) on the compensator. To adjust this, a 4 mm
and 6 mm Allen wrench will be needed. The adjust-
ment screw is facing the front of the pump, or
toward the engine.
d. First, using the 4 mm wrench, loosen the setscrew
on the side of the compensator (facing you) which is
in line with the adjustment screw. This is a jam nut
screw which holds the main adjustment from turn-
ing. Loosen it 1 turn.
Then using the 6 mm wrench adjust the main adjustment
clockwise to increase or counterclockwise to decrease. This is
the
maximum relief pressure for all functions governed by this
pump.
LS adjustment screw
6mm
LS set screw
4mm
7-11 N•m [6-8 lbf•ft]
Case drain port L1
0-10 bar [0-100 psi]
7/8-14
3/8 in
54-136 N•m
[40-100 lbf•ft]
Gauge port M2
0-300 bar [0-5000 psi]
9/16-18
1/4 in
34-68 N•m
[25-50 lbf•ft]
M14
6mm
27-35 N•m
[20-26 lbf•ft] LS/remote PC
signal port X
Figure 5-85. Load Sensing Control Adjustment
PC adjustment screw
6mm
PC set screw
4mm
7-11 N•m [6-8 lbf•ft]
Case drain po rt L1
0-10 bar [0-100 psi]
7/8-14
3/8 in
54-136 N• m
[40-100 lbf• f t]
Gauge port M2
0-300 bar [0-5000 psi]
9/16-18
1/4 in
34-68 N• m
[25-50 lbf• ft]
M14
6mm
27-35 N• m
[20-26 lbf• f t]
Figure 5-86. Pressure Compensation Control Adjustment